#include <stdio.h>
#include <unistd.h>

int global_value = 100;

int main()
{
    pid_t id = fork();
    if(id < 0)
    {
        printf("fork error\n");
        return 1;
    }
    else if(id == 0)
    {
        int cnt = 0;
        while(1)
        {
             printf("子进程:pid:%d,ppid:%d,global_value:%d,&global_value:%p\n",getpid(),getppid(),global_value,&global_value);
             sleep(1);
             cnt++;
             if(cnt == 10)
             {
                global_value = 300;
                printf("子进程更改了全局变量\n");
             }
        }
    }
    else
    {
        while(1)
        {
             printf("父进程:pid:%d,ppid:%d,global_value:%d,&global_value:%p\n",getpid(),getppid(),global_value,&global_value);
             sleep(2);
        }
    }
    return 0;
}

